(ABC News) - When Nikolas Evans was assaulted in a fight last year outside a bar in Austin, Texas, his mother's dreams for her 21-year-old son -- a college student with "a good head on his shoulders" -- evaporated.
Returning from a night of drinking, Nikolas and a friend were attacked on their way to catch a bus ride home. The fatal blow came when the slight son she called "Pea" was violently knocked sideways by an assailant and struck his temple on the ground.
Nikolas, initially left in the middle of the road, died 10 days later of a subdural hematoma.
"His brain never stopped swelling," said his mother, 43-year-old Missy Evans of Bedford, Texas. "I sat at a picnic table and bawled for an hour. I never cried so hard. I talk to him four times a day and see him twice a week and now nothing. I couldn't lose him. It was too important."
But now his mother is hoping for a legacy -- a grandchild culled from her son's sperm after his death on April 5, 2009. She has heard from hundreds of women who have offered to be egg donors or surrogate mothers for her future grandchild.
Advances in the fertility industry have allowed wives, fiances, girlfriends and even parents to seek post-mortem sperm retrieval when a man dies unexpectedly.
The first report of post-mortem sperm retrieval was in 1980 involving the case of a 30-year-old man who became brain dead after a car accident, according the journal "Human Reproduction."
A birth was first reported in 1999, but since then more than 1,000 such requests are made each year. Most do not result in pregnancy attempts.
"Often parents change their minds," said Dr. Daniel Williams, assistant professor of urology at University of Wisconsin-Madison.
In post-mortem sperm retrieval, sperm is surgically removed from the testes, epididymus and vas deferens then preserved in nitrogen vapor.
Frozen, it can be kept indefinitely, with "no obvious risk to offspring," according to Williams.
The science is easy, say medical experts, but the ethics are not so clear.
"It's an area that is steeped in ethical issues, emotional issues and financial issues," he told ABCNews.com. "These issues can become very challenging because there are no guidelines or laws or rules on how to handle the requests. Often they are handled on a case-by-case basis."
Many doctors suggest that parents like Evans, who are still grieving for a lost child, should have a "quarantine period" as they heal to consider all the ramifications of having a baby from sperm retrieval, including the welfare of the unborn child.
Ethicists Say Deceased Can't Consent
Ethicists worry that the deceased is fathering a child without consent and few younger men have living wills that would address the issue.
Large medical centers like Cornell University recommend that a panel of experts look at all aspects of the retrieval request before parents are allowed to take the next step.
Evans, who runs her own Web development company, said she was barraged with vitriol after she decided to retrieve and freeze Nikolas' sperm. Critics lambasted her for being unmarried, for her lack of formal religion and even accused her of trying to "find a replacement" for her son.
Some wondered how well the child will deal with a father who is dead and a biological mother who is anonymous.
"Everybody is telling me it's unethical what I am doing," said Evans. "But I raised him and he wanted children. I can't get him to film school at UCLA and I couldn't help him live his dream because someone has taken it away from him."
For Evans, the idea came as the family was preparing for her son's inevitable death. She discussed the idea with her longtime boyfriend, her ex-husband, her older son and other family members, who offered to be part of the child's life.
"He was an old soul and wanted kids," Evans said of Nikolas, who was interested in filmmaking, politics, music and old movies. She said he specifically said he wanted three children, all boys.
If the child is a boy, she said she would name it after her son's favorite author, Hunter S. Thompson.
"Nikolas had talked to me about how I was an only child and his cousin was an only child," said Evans. "He was going to fill my Christmases and birthdays with grandchildren."
(Just this week, Nikolas' assailant, Erik Skeeter, was sentenced to 10 months probation for manslaughter in a plea bargain.)
Evans sought permission from a probate judge to take ownership of the sperm and Nikolas' body was chilled to no more than 39.2 degrees.
A urologist donated her services and after five of his organs were donated, she retrieved Nikolas' sperm.
Finding an egg donor who will undergo injections and tests will cost at least $20,000. Hiring a surrogate to be inseminated and to carry the child could cost another $50,000.
But there are many challenges ahead. There is no guarantee Nikolas' sperm is viable or that in vitro fertilization will be successful.
Sperm must be collected within 24 to 36 hours of a death -- a "gray window" -- and even then, it may not be viable, according to Albert Anouna, director of the Sperm and Embryo Bank of New Jersey. Nikolas' sperm was collected 31 hours after death.
Post-Mortem Sperm Retrieval Expensive
The cost for surgical removal is about $3,000, according to Anouna, whose company has been asked to do five or 10 this year -- "not exactly an everyday occurrence."
Only about 1 in 500 requests are utilized, he said.
"I am not a psychologist, but the reason is that it's part of a closure," said Anouna told ABCNews.com. "The individual who asks for it either changes his mind or it's too expensive."
"It's the happiest when you get a thank you note," said Anouna, who has seen two successful pregnancies since he founded his company in 1981.
But often, post-mortem sperm retrieval itself is a failure.
In one case, Gisela Marrero of New York City had her longtime boyfriend's sperm retrieved post-mortem. Johnny Quintana, a concierge and auto mechanic, collapsed while watching television at age 31.
"The day before he passed away, we talked about planning for our future, buying an apartment and having another child," Marrero told the Daily News. "This was his wish. It's the last thing I can do for him."
Because Anouna's sperm bank follows strict ethical codes, Quintana's family had to go to court to prove the sperm was intended for one specific recipient who had an intimate relationship with the deceased.
Quintana's body was kept in cold storage at Jacobi Medical Center with an ice bag on his testicles. Semen was collected, but there was not enough sperm for artificial insemination.
But Missy Evans is optimistic a pregnancy might come from the 20 vials of sperm that were harvested from her son Nikolas, enough for multiple attempts at in vitro fertilization.
She is also certain Nikolas would have consented -- her reasoning in agreeing to donating his heart, liver, kidneys and pancreas.
"He helped five people live that day," said Evans. 'If you say I am no longer in charge, how can I give five gifts? I am happy about that, but why can't I have a gift? Why do I lose everything?"
But according to Art Caplan, chair of the department of medical ethics at the University of Pennsylvania in Philadelphia, "It's one thing to save a life and another thing to make a new one."
Organ Donation Didn't Consider Sperm
"The Uniform Anatomical Gift Act did not include gametes when it was written in 1980s," he told ABCNews.com. "No one was thinking of post-mortem sperm."
"Is the request from a relative close enough to know the wishes of the deceased for reproduction?" he asked. "Your wife or fiance may have more to say than your mother. We've seen situations where strangers showed up. Is this person in a position to parent? If an 80-year-old grandmother can't raise the children, who will she give it to?"
Caplan said grieving parents need a "cooling off period" to confront their motivation and resources for creating a child.
"You need to have a review by courts, hospitals should have ethics committee review mandatory and the law needs to catch up with technology," he said.
Dr. Jeanne O'Brien, assistant professor of urology at University of Rochester Medical Center in New York, said she understands the "pure pain" that parents feel when they lose a child.
"These people are in terrible pain beyond imagining and don't think beyond their loss," she told ABCNews.com. "These people have suffered a huge loss and they see this as a potential to ease their pain. If we sit down and have a frank discussion, we can bring it in to a better light."
Now, nearly a year after her son's sperm was collected, Missy Evans is surer than ever that she made the right choice and wants to help pass legislation that will make it easier for parents -- especially those who have lost sons in war -- to reap their sperm.
"My boyfriend and I are talking about getting married," she said. "We are looking into medical grant programs. We have our 401(k)s and what we make now -- we definitely make a good living. It could cost hundreds of thousands of dollars, but it's something I will never give up on."
"I know he would think this is OK," said Evans. "He would want me to do whatever I needed to do and I wanted something to live on."
ABC Affiliate WFAA reporter Janet St. James contributed to this report